T-square securing means



Nov. 13, 1951 H. A. CHAPIN 2,574,463

T SQUARE SECURING MEANS Filed DEC. 25, 1946 2 SHEETSSHEET 2 *2 S: k) aT? I A A%% Patented Nov. 13, 1951 UNITED STATES PATENT OFFlCE T-SQUARESECURING MEANS Harold Addison Chapin, San Jose, Calif.

Application December 23, 1946, Serial No. 717,875

2 Claims.

The present invention relates to means for holding the head of a Tsquare firmly and slidably against the side of a drafting-board when inuse.

As heretofore made the T square is held in contact with the board bypressure of the hand and sometimes will be allowed to slideinadvertently over a line previously made in ink and still fresh, insuch a manner as to smear the ink and ruin the drawing.

One object of the invention is to provide a device that can be easilyand quickly attached to the board and square that will effectuallyprevent its accidentally slipping and hold the blade of the square atright-angles to the board.

Another object of the invention is to provide resiliently controlledmeans for holding the square in position and instantly released forpermitting the easy manipulation of the square on the board and at thesame time prevent the tipping of the square on the board.

It is also an object of the invention to provide a device of thecharacter indicated that can be easily manipulated by the fingers of onehand.

In the drawing:

Figure 1 is a top plan view of my invention as attached to a square andpositioned on a board, parts being broken away.

Figure 2 is an enlarged sectional view on line 22 on Figure 1.

Figure 3 is an enlarged top plan view of my invention as arrangtd on a Tsquare.

Figure 4 is a bottom plan view of a square in position on a board, partsbeing broken away, and embodying my invention.

Figure 5 is a cross sectional view on the line 5-5 of Figure 2.

Referring now more particularly to the drawing, I show at l a draftingboard fitted on one edge with a strip of metal 2 to act as a smooth andtrue edge for the T square to slide on, this metal strip being slightlywider than the thickness of the blade head 4 of the T square inconjunction with which it is used. The opposite edge of the board isfitted with a strip of metal 3, this latter strip being in the form ofan angle bar, and placed with its top surface lying fiush with the topsurface of the board as shown.

The head of the T square, as mentioned, is shown at 4 with the bladeshowing at 5, the head end of the blade having a sheet of sheet metal 6bent thereover as shown to provide clearance for the blade on the boardand permit its sliding freely thereover, and to provide a slidingsurface for the member hereinafter described.

Passing through the blade head 4 and overlying end of blade 5 is a bolt1 supporting a knob 8 in fixed relation to the blade head 4 and blade 5,the said knob 8 having a groove 9 formed in its bottom end to permit thestrap H) to slide therethrough. I

The strap I0 is a fiat strip of sheet metal lying fiat on the topsurface of the blade 5 in parallel relation therewith and along itsmedian line, passing through the groove 9 and terminating in a straphead I l. The head I l is a heavy piece of sheet-metal bent into aU-shape when viewed endwise, the space between the top and bottom leavesof the U-shaped member being somewhat greater than the thickness of thestrap it which it encompasses and to which it is bolted as at l2. Inthis space between the top and bottom leaves of the U-shaped member isplaced a spring is with one end bearing against the member and the otherend bearing against the adjacent edge of the metal member 6. Disposingthe spring l3 in this manner enables it to urge the strap head I l andconsequently the strap l0 outwardly with respect to the blade 5.

The strap ID has a slot [4 formed therein through which the bolt '1passes and which permits the strap to slide on blade 5. Adjacent thefree end of blade 5 is bolted as at I5 a shoe It, a slot I! in blade 5allowing the bolt [6 to slide backwards and forwards in the blade, theshoe I6 being supported below the blade 5 to have sliding engagementwith the angle bar 3.

Normally the spring l3 urges the shoe l6 against the angle bar 3 belowits top flange and thus holds the blade head 4 snugly against the metalstrip 2 and holds the T square firmly in position. By hooking the thumbof the left hand around the knob 8 the fingers of that hand may befreely used to press upon the strap head II and so re lease the springpressure forcing the shoe it into contact with the metal strip 3 andpermitting the free movement of the blade 5.

The slots [4 and I! permit the strap in to be moved lengthwise of theblade 5 for releasing the pressure against strip 3, and also to permitthe pressure of spring l3 to return that pressure instantly when sodesired by the operator.

Two guide members, preferably resilient, are shown at I8l8 fastened tothe underside of the metal strip 2 to pass under and bear against thebottom front edge of the head 4. These guide members operate to hold theblade head 4 in its proper relation to the top surface of the draftingboard, that is, in most cases with its top surface aligned fiush withthe top surface of the board.

it is to be noted that the sheet metal strip 6 which is disposed overthe head end of the blade 5 provides reinforcing bearings spaced in thedirection of the length of the bolt 1 to aid in sustaining the same whenthe T-square is actuated by the knob 8.

In the manner described the T-square may be instantly adjusted along thelength of the board and yet at. all times it is held against accidentalmovement:

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is:

l. The combination of a T-square including a;-

blade, and a transversely extending head secured to one end thereof andhaving a straight inner wall for engagement with the edge of adraftingboard, a U-shaped holder of relatively thin stock carrying the head endof the blade, one leg of the U-shaped holder being disposed between theT-square head and the blade whereby to space the latter slightlyaboveth'e plane of the top of a drafting board, an elongated'boltextending through said head, blade and blade holder; a knob mounted onthe projected-end of said bolt above said blade and head, an, elongatedflat metal strap extending lengthwise of saidblade, one endof said strapnormally projectingbeyond the outer edge of said head and having adown-turned portion disposed in opposition to the outer edge of saidhead, said strap having a lineal slot through which saidknob carryingbolt-extends, a vertically extending pin secured to the strap adjacentitsrotheriend', the;

blade having, a slot through which said pin extends to a point below theundersurfacevof said blade, a shoe carried by the lower end of-said pinand positioned to engage the edge ofthe drafting board opposite to thatengaged by the T-square head, said knob having a groove-in its 4 bottomsurface through which said strap is adapted to slide, and spring meansinterposed between the down-turned end of said strap and the rear edgeof said blade and its U-shaped holder.

2. The combination of a T-square including a blade, and a transverselyextending head secured to one end thereof and having a straight innerwall for engagement with the edge of a drafting board,,an elongatedboltextendingrthrough said head and=bladeand projecting above the topsurface of the latter, a knob mounted on the projected end of said boltabove said blade and head, an elongated flat metal strap extendinglengthwise 'of said blade, one end of said strap normally projectingbeyond the outer edge of said head and having a down-turned portiondisposed irropposition to the outer edge of said head, said strap havinga lineal slot through which said knob-carrying bolt extends, a dependingdraftin board-edge-engaging shoe element carried by said strap-at theendremote from the knob, said blade and strap havin 00- operating guidemeans-adjacent said last men-- tioned end of said strap.

HAROLD ADDISON CHAPIN.

REFERENCES CITED Thefollbwlngreferences-'are'of record in thefile'ofthispatent:

UNITED STATES PATENTS Number Name Date 282,248. Weidenmann' July 31-,1883 v 1,419,354 Boon- -i. June 13, 1922' 2,085,304- Farrell June 29,193'! 2,326,301 Leffel- Mag 10, 1943 FOREIGN PATENTS Number Country Date21,402 Great Britain Sept. 20, 1909= 376,843 Germany June 5, 1923

